1. Field of the Invention
The present invention relates to a circuit board having, for example, a high speed and high frequency electronic circuit mounted thereon, and particularly relates to amelioration in power supply wiring wired immediately below a high speed LSI, such as a DDR memory interface.
2. Description of the Related Art
With the progress in multilayer printed board techniques, many of electronic circuit boards have a surface mount LSI mounted thereon.
Surface mount electronic circuit boards are made by planar and direct solder mounting on a surface of the circuit board. As a package using such a surface mount technique, there are ball grid array (BGA) packages and the like.
In a BGA package, solder balls (or may also be referred to as bumps) are arranged as electrodes on the back side of the package in a grid and at a regular interval. Such a BGA package is suitable for high density packaging.
Multilayer printed circuit boards are disclosed in, for example, Japanese Unexamined Patent Application Publication Nos. 9-326451, 10-223997, and 2001-53449.